Medical device with shield having a retractable needle

ABSTRACT

Needle-bearing medical devices are provided for fluid infusion, fluid transfusion, and inserting a guide wire. After use the needle is shielded to render the contaminated needle safe to prevent inadvertent needle sticks. The device includes a housing and a needle having a sharpened tip. A biasing element biases the needle toward a position in which the sharpened tip is shielded.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/837,539, filed Apr. 18, 2001, set to issue as U.S. Pat. No. 6,786,875on Sep. 7, 2004, which is a continuation-in-part of U.S. applicationSer. No. 09/628,180, filed on Jul. 28, 2000, which issued as U.S. Pat.No. 6,398,743 on Jun. 4, 2002. This application also claims priority toU.S. Provisional Application No. 60/198,032, filed Apr. 18, 2000 andU.S. Provisional Application No. 60/223,651 filed Aug. 7, 2000. Each ofthe foregoing applications is hereby incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to medical devices for fluid infusion,fluid transfusion, and inserting a guide wire into a patient. In aparticular, the present invention relates to medical devices having asharpened needle used for introducing a guide wire into a patient. Theneedle pierces the patient to provide vascular access, and the guidewire is then inserted into the patient through the needle. After use,the sharpened needle is protected against inadvertent contact. Morespecifically, after use, the needle is retracted so that the sharpenedtip of the needle is enclosed within the device.

BACKGROUND

Various types of medical devices employ a needle for piercing the skinof a patient for diagnostic or therapeutic purposes. One such device isan Epidural needle for introducing medicine to a patient during anEpidural procedure. Another such device is a device for infusing orwithdrawing blood or plasma in a patient. Yet another such device is adevice for introducing a guidewire into a patient. The guidewire is thenused to guide a separate element such as an enlarged bore introducersheath and dilator into the patient. Once the guidewire is properlypositioned, the insertion device is withdrawn leaving the guidewire inplace in the blood vessel. Handling of such medical devices after theneedle is withdrawn from the patient can result in transmission ofvarious pathogens, most notably human immune virus (HIV), due to ininadvertent needle stick to medical personnel.

SUMMARY OF THE INVENTION

In light of the foregoing, the present invention provides a method andapparatus for inserting a needle into a patient and rendering the devicesafe after use to prevent inadvertent contact with the contaminatedneedle. The present invention also provides a method and apparatus forinserting a guide wire into a patient and rendering the device safeafter use to prevent inadvertent contact with the contaminated needle.

In accordance with one aspect of the invention, a medical device isprovided that has a needle having a sharpened tip projecting forwardlyfrom a housing. Prior to use a shield sheaths a portion of the needle sothat the sharpened tip projects forwardly from the sheath. After use thesharpened tip is retracted into the shield. A biasing element biases theneedle toward the retracted position.

In accordance with another aspect of the invention, a medical device isprovided that has a needle having a sharpened tip projecting forwardlyfrom a housing. Prior to use a shield sheaths a portion of the needle sothat the sharpened tip projects forwardly from the sheath. After use thesharpened tip is retracted into the shield. A biasing element biases theneedle toward the retracted position, and a hub connected with theneedle includes a guide for guiding a guide wire into the patientthrough the needle and a connector for attaching a fluid reservoir tothe device.

The present invention also provides a medical device having a needlehaving a sharpened tip projecting forwardly from a housing. After use,the sharpened tip of the needle is shielded against inadvertent contact.A biasing element is operable to displace the sharpened tip of theneedle into the shielded position. The device includes a connector forattaching a fluid collection device to the housing. The connector alsoincludes a first port, and the device includes a second port in fluidcommunication with the needle. An adapter associated with the secondport is configured for receiving and guiding a guide wire through thesecond port and into the needle.

The present invention also provides a method for inserting a guide wireinto a patient using a needle-bearing medical device having first andsecond ports. According to the method, a needle is inserted into apatient and blood is aspirated through the first port. The needle isretracted so that the sharpened tip of the needle is shielded to protectagainst inadvertent contact. A guide wire is then inserted into thepatient through the second port.

The present invention also provides a method for inserting a guide wireinto a patient using a needle-bearing medical device having a port. Theneedle is inserted into the patient and a fluid reservoir is attached tothe port for collecting blood from the patient. The fluid collectiondevice is detached from the port and a guide wire is inserted into thepatient through the device. The needle is retracted to shield the needleto prevent inadvertent contact with the contaminated needle.

Accordingly, when configured and used as described above, the presentinvention provides a safe and effective method for infusing medicine,transfusing blood or plasma, or inserting a guide wire into a patient.In addition, the device is designed to improve manufacturingefficiencies thereby reducing the overall cost of the device.

DESCRIPTION OF THE DRAWINGS

The foregoing summary as well as the following description will bebetter understood when read in conjunction with the figures in which:

FIG. 1 is a plan view of a medical device for fluid transfusion having aretractable needle;

FIG. 2 is a cross-sectional view of the medical device illustrated inFIG. 1, taken along line 2—2;

FIG. 3 is a cross-sectional view of the medical device illustrated inFIG. 2, illustrating the device in a retracted position.

FIG. 4 is a plan view of a medical device for fluid transfusion having aretractable needle;

FIG. 5 is a side elevational view of the medical device illustrated inFIG. 4;

FIG. 6 is a cross-sectional view of the medical device illustrated inFIG. 4, taken along line 6—6;

FIG. 7 is a cross-sectional view of the medical device illustrated inFIG. 6, illustrating the device in a retracted position;

FIG. 8 is an exploded perspective view of the medical device illustratedin FIG. 4;

FIG. 9 is an enlarged fragmentary exploded perspective view of thebarrel of the medical device illustrated in FIG. 4;

FIG. 10 is a cross-sectional view of an alternative embodiment of amedical device for fluid transfusion having a retractable needle;

FIG. 11 is a cross-sectional view of the device illustrated in FIG. 10,illustrating the device in a retracted position.

FIG. 12 is a cross-sectional view of a medical device having aretractable needle for inserting a guide wire;

FIG. 13 is a cross-sectional view of the medical device illustrated inFIG. 12, illustrating the needle in a retracted position,

FIG. 14 is an enlarged fragmentary cross-sectional view of the portiondesignated A of the medical device illustrated in FIG. 13;

FIG. 15 is a cross-sectional view of an alternate embodiment of amedical device having a retractable needle for inserting a guide wire;

FIG. 16 is a cross-sectional view of the medical device illustrated inFIG. 15, illustrating the needle in a retracted position;

FIG. 17 is a side view partially in section of the medical deviceillustrated in FIG. 16 in combination with a guide wire feeder,illustrating the device inserted into a patient; and

FIG. 18 is a side view partially in section of the medical deviceillustrated in FIG. 16 in combination with a guide wire gripper,illustrating the device inserted into a patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the figures in general and to FIG. 1 specifically, amedical device for fluid infusion is designated generally 10. The device10 includes a sharpened needle 65 for inserting the device into apatient. After the needle is inserted into the patient, fluid can beinfused into the patient through the needle. After use, the needle 65 isretracted into the device 10 so that the sharpened tip of the needle isenclosed, thereby preventing inadvertent contact with the contaminatedneedle.

Referring now to FIGS. 1 and 2, the device includes an elongated hollowbarrel 20. The needle 65 projects forwardly from the barrel, with asheath 30 surrounding the length of the needle. The needle 65 isattached to a needle hub 40 disposed within the barrel 20. A spring 60disposed within the barrel biases the needle hub 40 and the attachedneedle 65 rearwardly toward a retracted position. A needle retainer 42releasably retains the needle hub against the bias of the spring 60. Aconnector hub 50 at the rearward end of the device 10 allows a fluidsource to be attached to the device for infusing fluid, such asmedicinal fluid, through the needle and into the patient.

The medical professional using the device 10 can retract the needle bypressing a button 43, which disengages the needle retainer 42. Thespring 60 then propels the needle 65 rearwardly so that the sharpenedtip of the needle is enclosed within the shield 30. In this way, thecontaminated needle 65 is protected against inadvertent contact.

The details of the device will now be explained in greater detail. Asshown in FIG. 2, the barrel is a generally cylindrical barrel having ahollow central bore. A locking aperture 22 in the sidewall of the barrel20 is configured to cooperate with the needle retainer 42 as describedfurther below. The rearward end of the barrel is generally open forreceiving the needle hub 40. The forward end of the barrel 20 isgenerally closed, having a reduced diameter opening through which theneedle 65 extends. Optionally, a seal 35, such as an O-ring may beprovided to form a fluid seal between the reduced diameter opening andthe needle 65 to prevent fluid from leaking from the shield 30 into thebarrel 20 after retraction.

Although the barrel 20 may be formed as a single piece, in the presentinstance, the barrel is formed in two portions that are snap-fittogether. Alternatively, the two portions can be connected by ultrasonicwelding or adhesive. In addition, the barrel may include a pair ofopposing axial slots formed in the interior surface of the barrel,adjacent the rearward end of the barrel. Such slots form a guide trackthat cooperates with the needle hub 40 to guide the needle 60 duringretraction. Additionally, the slots prevent the button 43 from beingtwisted relative to the locking aperture 22 when a fluid collectiondevice is attached to the device 10.

The barrel 20 further includes a flange 27 projecting radially inwardlyfrom the interior surface of the barrel, adjacent the rearward end ofthe barrel. The flange 27 forms a stop that cooperates with the needlehub 40 to limit rearward displacement of the needle hub, which in turnlimits the retraction of the needle.

Preferably, a push bar or wing 90 is attached to the housing 20. Thepush bar 90 is a generally planar surface disposed substantially normalto the axis of the housing. In this way, insertion force can be appliedto the push bar 90 to aid in inserting the device 10 into the patient.

Referring again to FIGS. 1 and 2, the details of the needle hub 40 areillustrated. The needle hub 40 is generally cylindrical having aninternal bore for receiving the needle 65. Preferably, the needleretainer 42 is integrally formed with the needle hub 40. The needleretainer includes an axially elongated radially deformable arm with alatch or button 43. The button 43 is configured to cooperate with thelocking aperture 22 in the barrel, to releasably engage the needle hub40 with the barrel 20. The forward end of the needle hub 40 flaresoutwardly forming a circumferential flange 45 having an externaldiameter corresponding to the central bore of the barrel. In this way,as the needle hub 40 is displaced rearwardly during retraction, theflange 45 slides along the interior bore to guide the needle hub.

The needle 65 is operable between a projecting position illustrated inFIG. 2 and a retracted position illustrated in FIG. 3. In the projectingposition, the needle projects forwardly from the barrel so that thesharpened tip of the needle is exposed to pierce the patient and guidethe shield 30 into the patient. In the retracted position, the sharpenedtip of the needle is disposed within the shield 30 to preventinadvertent contact with the contaminated needle. The spring 60 biasesthe needle 65 rearwardly toward the retracted position. The needleretainer 42 releasably retains the needle 65 in the projecting positionagainst the bias of the spring 60.

The needle 65 extends through the central bore of the needle hub 40, andthrough the opening in the barrel tip 25 so that the sharpened tip ofthe needle projects forwardly from the barrel. The shield 30 is fixedlyattached to the barrel tip 25 so that the shield also projects forwardlyfrom the barrel 20. More specifically, a shield connector 32 isconfigured to cooperate with the barrel tip 25 to fixedly attach theshield to the barrel. The shield connector 32 includes an internalcavity configured to form a snap fit with the barrel tip 25. The shield30 is fixedly attached to the shield connector 32, such as by adhesiveor welding. In this way, the shield 30 is fixedly attached to the barrel20 when the shield connector 32 is snapped onto the barrel tip 25.

The shield 30 is in the form of a relatively thin-walled cannula,overlying the needle 65 in telescoping relation. Specifically, theinterior diameter of the shield is substantially the same as theexternal diameter of the needle 65. Preferably, the interior diameter ofthe shield 30 is the same as or several thousandths of an inch largerthan the external diameter of the needle so that the needle 65 canreadily slide within the shield.

As shown in FIG. 3, the forward end of the shield 30 tapers inwardlyforming a thin wall with a feather edge, which provides a smoothtransition between the forward end of the shield 30 and the needle 65.In this way, when the needle 65 is inserted into the patient, theoverlying shield 30 is also readily inserted into the patient.

A stop limits the rearward travel of the needle hub 40 to limit thedistance that the needle 65 is retracted. Specifically, the forward endof the needle hub flares outwardly forming an enlarged head 45. Theenlarged head 45 engages the flange 27 on the interior of the barrel 20when the needle is retracted. In this way, the engagement between theflange 27 and the enlarged head 45 limits the rearward displacement ofthe needle 65.

Preferably, prior to retraction, the axial distance between the flange27 and the enlarged head 45 is less than the length of the shield 30that projects forwardly from the barrel 20. More specifically,preferably the axial distance is less than half the length of the shieldthat projects forwardly from the barrel 20. It is further preferablethat the axial distance be substantially less than one quarter thelength of the shield that projects from the barrel. In this way, afterretraction, the sharpened tip of the needle is enclosed within theshield 30, rather than being retracted into the barrel 20.

The device 10 further includes elements for impeding re-extension of theneedle 65 after retraction, so that the contaminated sharpened tip ofthe needle is not exposed. Specifically, a pair of opposing radiallydeformable latches are integrally formed in the side of the barrel 20. Apair of cooperating notches are formed in the needle hub 40. When theneedle hub 40 retracts rearwardly, the needle hub deforms the latchesradially outwardly so that the needle hub is displaced between thelatches. When the needle hub is displaced rearwardly so that the notcheson the needle hub are aligned with the latches, the latches, which arebiased radially inwardly, are displaced inwardly into engagement withthe notches, retaining the needle hub and needle against forwarddisplacement. In this way, the latches and notches prevent the needlefrom being re-extended from the shield after retraction.

A connector hub 50 attached to the needle hub 40 provides an access portfor attaching a fluid reservoir to the device for infusing fluid intothe patient. The connector hub 50 includes a central bore in fluidcommunication with the needle 65. In the present instance, the rearwardend of the needle 65 is connected with the connector hub 50.

The connector hub 50 has an open rearward end and preferably forms aconnector in the form of a Luer fitting for attaching a medical device,such as a fluid reservoir as discussed further below. In addition,preferably a lock 56 is formed on the rearward end of the connector hubfor locking the separate device to the connector hub. More specifically,preferably, the lock 56 is a threaded Luer lock formed on the exteriorof the connector hub.

In the present instance, the needle hub 40 and connector hub 50 havebeen described as two separate elements connected together. However, thetwo elements can alternatively be formed as a single element.

Retracting the needle into the shield rather than the barrel has severalbenefits. For instance, the overall length of the barrel can be reducedbecause the barrel need not be long enough to accommodate the retractedneedle.

After use, the shield 30 shields the sharpened tip of the needle 65against inadvertent contact. Preferably, the shield 30 is somewhatflexible. In addition, the shield is preferably formed with sufficientcolumn strength to prevent the shield 30 from collapsing axially inresponse to an axial force after retraction. This columnar strengthprevents the shield from readily buckling axially after retraction,which could expose the contaminated needle. In other words, the shield30 is preferably laterally flexible, but is substantially axiallyincompressible. In addition, preferably the shield is substantiallypuncture resistant, so that the needle will not puncture the shield ifthe shield buckles or compress. In this way, the shield protects thecontaminated needle after retraction. In the present instance the shieldis formed of Teflon. However, a variety of other known plastic materialsmay be used to form the shield.

Configured in this way, the device 10 is preferably used to infuse fluidinto a patient as follows. The needle 65 and shield pierce the skin of apatient and the needle is advanced to the proper location within thepatient. In certain instances, additional insertion force may be appliedby pressing forwardly on the push bar 90. This is particularly helpfulin situations in which the forward tip of the needle need not be sharpand/or the needle must be inserted through tough material, such as inneedles used for blunt dissection. For instance, when inserting anEpidural needle, the needle is relatively dull and is inserted adjacentthe spinal cord, without piercing the spinal cord. In such instancesadditional force must be applied to insert the needle to the properlocation to apply anesthesia. Once the needle is in place within thepatient, the needle is retracted into the shield, to cover the needlewhile the shield is within the patient. If desired, a catheter may beinserted into the patient through the needle and shield. A fluid sourcecan then be attached to the catheter to deliver medicinal fluid to thepatient. Alternatively, the fluid source may be attached to theconnector hub 50 and medicinal fluid may be delivered to the patientthrough the needle and shield. After use, the device 10 is withdrawnfrom the patient. Since the needle is shielded, the used device may bediscarded without risk of inadvertent contact with the contaminatedneedle.

Referring now to FIG. 4 specifically, a medical device for fluidtransfusion is designated generally 100. As discussed further below,preferably the device is particularly suited for use in connection withhemodialysis, which utilizes a pair of the devices. Specifically, one isinserted into the patient to withdraw blood, which is fed to ahemodialysis machine. The second device 100 is inserted into the patientto return the blood from the dialysis machine. In other words, bloodflows from the patient through one of the devices, into the hemodialysismachine, and then returns through the second device while the patient ishooked up to the hemodialysis machine.

The device 100 includes a sharpened needle 65 for inserting the deviceintravascularly. The needle 165 is in fluid communication with tubing172, which in turn is connected with a dialysis machine or fluidreservoir. After the needle is inserted into the patient, fluid caneither be withdrawn from the patient through the needle and collected ina reservoir or container attached to the tubing 172, or fluid can beinfused into the patient through the needle. After use, the needle 165is retracted into the device 100 so that the sharpened tip of the needleis enclosed, thereby preventing inadvertent contact with thecontaminated needle.

Referring now to FIGS. 6 and 7, the device includes an elongated hollowhousing 120. The needle 165 projects forwardly from the housing, with asheath 130 surrounding the length of the needle. The needle 165 isattached to a needle hub 140 disposed within the housing 120. A spring160 disposed within the housing biases the needle hub 140 and theattached needle 165 rearwardly toward a retracted position. A needleretainer 142 releasably retains the needle hub against the bias of thespring 160. The tubing 172 is attached to the rearward end of the needlehub 140 so that the needle 165 is in fluid communication with thetubing. A Luer fitting 174 at the rearward end of the tubing 172 allowsthe tubing to be readily connected with a dialysis machine or a fluidreservoir. In addition, a clamp 170 attached to the tubing 172 allowsthe medical professional to control the transfusion of fluid byselectively pinching the tubing with the clamp 174.

After insertion, the medical professional using the device 100 presses abutton 43, which disengages the needle retainer 142, and the spring 160propels the needle 165 rearwardly so that the sharpened tip of theneedle is enclosed within the shield 130. In this way, the needle 165 isshielded to prevent the needle from inadvertently damaging the patientduring use and to prevent inadvertent contact with the contaminatedneedle after use.

As shown in FIGS. 4–6, the housing is a generally cylindrical barrelhaving a hollow central bore 124. A locking aperture 122 in the sidewallof the housing 120 is configured to cooperate with the needle retainer142 as described further below. The rearward end of the housing flaresoutwardly having a larger diameter than the forward portion of thehousing. The rearward end of the housing is generally open for receivingthe needle hub 140 and the tubing 172. The forward end of the housing120 is open. A separate tip 125 fixedly attached to the forward end ofthe housing forms a reduced diameter opening at the forward end of thehousing through which the needle 165 extends. As shown in FIG. 9, thebarrel includes a pair of opposing circumferential slots for receiving alocking clip 150 as will be discussed further below.

A pair of wings 155 are attached to the housing 120. The wings 155 areattached to a central hub that circumscribes the housing 120. A reliefline located between each wing and the central hub forms a living hingesso that the wings can be folded up during the insertion procedure. Afterinsertion, the wings 155 are folded flat against the skin of the patientand taped to the patient to retain the device on the patient duringfluid transfusion.

Referring again to FIGS. 6 and 7, the details of the needle hub 140 areillustrated. The needle hub 140 is generally cylindrical having aninternal bore for receiving the needle 165. Preferably, the needleretainer 142 is integrally formed with the needle hub 140. The needleretainer includes an axially elongated radially deformable arm with alatch or button 143. The button 143 is configured to cooperate with thelocking aperture 122 in the housing, to releasably engage the needle hub140 with the housing 120. The forward end of the needle hub 140 flaresoutwardly forming a circumferential flange 145 having an externaldiameter corresponding to the central bore 124 of the housing. In thisway, as the needle hub 140 is displaced rearwardly during retraction,the flange 145 slides along the interior bore 124 to guide the needlehub.

The needle 165 is operable between a projecting position illustrated inFIG. 6 and a retracted position illustrated in FIG. 7. In the projectingposition, the needle projects forwardly from the housing so that thesharpened tip of the needle is exposed to pierce the patient and guidethe shield 130 into the patient. In the retracted position, thesharpened tip of the needle is disposed within the shield 130 to preventinadvertent contact with the contaminated needle. The spring 160 biasesthe needle 165 rearwardly toward the retracted position. The needleretainer 142 releasably retains the needle 165 in the projectingposition against the bias of the spring 160.

The needle 165 extends through the central bore of the needle hub 140,and through the opening in the housing tip 125 so that the sharpened tipof the needle projects forwardly from the housing. The shield 130 isfixedly attached to the housing tip 125 so that the shield also projectsforwardly from the housing 120. The shield 130 is in the form of arelatively thin-walled cannula, overlying the needle 165 in telescopingrelation. The forward end of the shield 130 tapers inwardly forming aknife edge which provides a smooth transition between the forward end ofthe shield 130 and the needle 165. In this way, when the needle 165 isinserted into the patient, the overlying shield 130 is also readilyinserted into the patient.

A stop limits the rearward travel of the needle hub 140 to limit thedistance that the needle 165 is retracted. Specifically, as shown inFIG. 9, a horseshoe-shaped locking clip 150 circumscribes the housing120. The locking clip 150 includes a pair of locking tabs 152 projectingradially inwardly. When the locking clip 150 is attached to the housingthe locking tabs 152 project radially inwardly through the slots 129 inthe side of the housing. The locking tabs 152 engage the flange 145 onthe needle hub 140 when the needle is retracted. In this way, theengagement between the locking tabs 152 and the flange 145 limit therearward displacement of the needle 165.

Preferably, prior to retraction, the axial distance between the lockingtabs 152 and the flange 145 is less than the length of the shield thatprojects forwardly from the housing 120. More specifically, preferablythe axial distance is less than half the length of the shield thatprojects forwardly from the housing 120. In this way, after retractionthe sharpened tip of the needle is enclosed within the shield 130,rather than being retracted into the housing 120.

Retracting the needle into the shield rather than the housing hasseveral benefits. The overall length of the housing can be reducedbecause the housing need not be long enough to accommodate the retractedneedle. In addition, the needle 165 provides support for the shield 130to prevent the shield frown collapsing or buckling radially inwardly inresponse to external forces. For instance, in one application the device100 is used in conjunction with an elastomeric shunt having a pierceablewall. The shunt joins one of the patient's vein's with one of thepatient's arteries. The shunt is formed of an elastomeric material, andthe device 100 is inserted into the shunt by piercing the sidewall ofthe shunt and advancing the device into the shunt so that the needle andshield are in fluid communication with the patient's vein and/or artery.While the device 100 is inserted into the shunt, the medicalprofessional actuates retraction by depressing the button 143. Theneedle retainer 142 is thereby displaced radially inwardly out ofengagement with the housing, and the spring 160 displaces the needle 165rearwardly into the retracted position. As shown in FIG. 7, the needleremains within the shield 130 after retraction. Since the shield 130 isstill disposed within the shunt after retraction, the sidewall of theelastomeric shunt will tend to press radially inwardly against the wallsof the shield. The rigidity of the needle prevents the sidewall of theshunt frown collapsing the shield, which would cut off fluid transfusionthrough the device.

After use, the shield 130 shields the sharpened tip of the needle 165against inadvertent contact. Preferably, the shield 130 is somewhatflexible so that the device 100 is more comfortable for the patient 128while it is inserted in the patient. In addition, the shield is formedwith sufficient columns strength to prevent the shield 130 frowncollapsing axially in response to an axial force after retraction. Thiscolumnar strength prevents the shield frown readily buckling axiallyafter retraction, which could expose the contaminated needle.

Referring to FIGS. 6 and 8, the device is assembled as follows. Thewings 155 are attached to the housing 120 and the seal 157 and sprint160 are inserted into the housing through the rearward open end of thehousing. The needle hub 140 is inserted into the central bore 124 of thehousing so that needle hub bears against the spring and the button 143engages the locking aperture 122. The seal provides a fluid-tight sealto prevent fluid from leaking into the housing between the shield andthe needle. After the needle hub is inserted into the housing, thelocking clip 150 is snapped onto the housing. The needle is theninserted through the forward end of the housing until the rearward endof the needle is disposed within the needle hub 140. After the needle islocated within the needle hub, the needle is bonded to the needle hub.The tip 125 and attached shield 130 are then attached to the forward endof the housing to capture the spring between the tip and the needle hub.

In the embodiment illustrated in FIGS. 4–9, the device is described asusing a one-piece housing. It may be desirable to provide a two-piecebarrel so that the needle, and needle are exposed after assembly. Such astructure is disclosed in FIGS. 10–11, in which elements similar to theelements in the first embodiment are designated with like referencenumbers with the addition of 200s.

Referring to FIGS. 10–11, the device 200 includes a forward housing 220and a rearward housing 221. During assembly, the needle hub 240 isinserted into the forward housing 220. The rearward end of the needlehub 240 projects rearwardly from the forward housing 220. Since theneedle hub 240 and needle 265 are exposed, adhesive can be readilyapplied to bond the needle to the needle hub. The rearward housing 221is then attached to the forward housing 220 to enclose the needle hub240. The rearward housing 221 includes a flange 223 that cooperates withthe needle retainer to limit the rearward retraction of the needle 265.

In another embodiment of the present invention, referring now to FIG. 12specifically, a medical device for inserting a guide wire is designatedgenerally 300. The device 300 includes a sharpened needle 365 forinserting the device vascularly. After the needle is inserted into thepatient the needle may be retracted into the device 300 so that thesharpened tip of the needle is enclosed. A guide wire can then beinserted into the patient through the needle. After use, the device 300is withdrawn with the needle safely shielded.

Referring now to FIGS. 12 and 13, the device includes an elongatedhollow barrel 320. The needle 365 projects forwardly from the barrel,with a sheath 330 surrounding the length of the needle. The needle 365is attached to a needle hub 340 disposed within the barrel 320. A spring360 disposed within the barrel biases the needle hub 340 and theattached needle 365 rearwardly toward a retracted position. A needleretainer 342 releasably retains the needle hub against the bias of thespring 360. A port at the rearward end of the device 300 provides accessfor a guide wire 368, so that the guide wire can be threaded into thepatient through the needle 365.

The medical professional using the device 300 can retract the needle bypressing a button 343, which disengages the needle retainer 342. Thespring 360 then propels the needle 365 rearwardly so that the sharpenedtip of the needle is enclosed within the shield 330. In this way, thecontaminated needle 365 is protected against inadvertent contact.

As shown in FIG. 12, the barrel is a generally cylindrical barrel havinga hollow central bore. A locking aperture 322 in the sidewall of thebarrel 320 is configured to cooperate with the needle retainer 342 asdescribed further below. The rearward end of the barrel is generallyopen for receiving the needle hub 340 and a connector hub 350. Theforward end of the barrel 320 is generally closed, having a reduceddiameter opening through which the needle 365 extends. Preferably, aseal 335, such as an O-ring forms a fluid seal between the reduceddiameter opening and the needle 365 to prevent fluid from leaking fromthe shield 330 into the barrel 320 after retraction.

A pair of opposing axial slots 328 are formed in the interior surface ofthe barrel, adjacent the rearward end of the barrel. The slots 328 forma guide track that cooperates with the connector hub 350 to guide theneedle 360 during retraction, as is discussed further below.Additionally, the slots 328 cooperate with the connector hub 350 toprevent the button 343 from being twisted relative to the lockingaperture 322 when a fluid collection device is attached to the device300 as is discussed further below. Although the barrel 320 may be formedas a single piece, in the present instance, the barrel is formed in twoportions that are snap-fit together. Alternatively, the two portions canbe connected by ultrasonic welding or adhesive.

The barrel 320 further includes a flange 327 projecting radiallyinwardly from the interior surface of the barrel, intermediate thelength of the barrel. The flange 327 forms a stop that cooperates withthe needle hub 340 to limit rearward displacement of the needle hub,which in turn limits the retraction of the needle. A keyway in theflange provides clearance for the button to pass through the flange 327during retraction

Referring again to FIGS. 12 and 13, the details of the needle hub 340are illustrated. The needle hub 340 is generally cylindrical having aninternal bore for receiving the needle 365. Preferably, the needleretainer 342 is integrally formed with the needle hub 340. The needleretainer includes an axially elongated radially deformable arm with alatch or button 343. The button 343 is configured to cooperate with thelocking aperture 322 in the barrel, to releasably engage the needle hub340 with the barrel 320. The forward end of the needle hub 340 flaresoutwardly forming a circumferential flange 345 having an externaldiameter corresponding to the central bore of the barrel. In this way,as the needle hub 340 is displaced rearwardly during retraction, theflange 345 slides along the interior bore to guide the needle hub.

The needle 365 is operable between a projecting position illustrated inFIG. 12 and a retracted position illustrated in FIG. 13. In theprojecting position, the needle projects forwardly from the barrel sothat the sharpened tip of the needle is exposed to pierce the patientand guide the shield 330 into the patient. In the retracted position,the sharpened tip of the needle is disposed within the shield 330 toprevent inadvertent contact with the contaminated needle. The spring 360biases the needle 365 rearwardly toward the retracted position. Theneedle retainer 342 releasably retains the needle 365 in the projectingposition against the bias of the spring 360.

The needle 365 extends through the central bore of the needle hub 340,and through the opening in the barrel tip 325 so that the sharpened tipof the needle projects forwardly from the barrel. The shield 330 isfixedly attached to the barrel tip 325 so that the shield also projectsforwardly from the barrel 320. More specifically, the forward end of thebarrel 320 forms a cavity or socket. A shield connector 332 isconfigured to cooperate with the cavity to fixedly attach the shield tothe barrel. The shield connector 332 includes an internal boreapproximately the same as the external diameter of the shield 330. Theshield connector 332 forms an interference fit with the cavity on thebarrel, which in turn provides an interference fit between the shieldconnector and the shield 330, thereby attaching the shield to thebarrel. Alternatively, the shield 330 can be bonded to the shieldconnector 332. The depth in which the shield connector 332 is insertedinto the cavity can be varied so that the length of the shield 330overlapping the needle 365 can be varied. In this way the length of theneedle 365 projecting forwardly from the shield can be controlled duringmanufacture.

The shield 330 is in the form of a relatively thin-walled cannula,overlying the needle 365 in telescoping relation. Specifically, theinterior diameter of the shield is substantially the same as theexternal diameter of the needle 365. Preferably, the interior diameterof the shield 330 is the same as or several thousandths of an inchlarger than the external diameter of the needle so that the needle 365can readily slide within the shield.

As shown in FIG. 14, the forward end of the shield 330 tapers inwardlyforming a thin wall with a feather edge, which provides a smoothtransition between the forward end of the shield 330 and the needle 365.In this way, when the needle 365 is inserted into the patient's vein orartery, the overlying shield 330 is also readily inserted into thepatient's vein or artery.

A stop limits the rearward travel of the needle hub 340 to limit thedistance that the needle 365 is retracted. Specifically, the forward endof the needle hub flares outwardly forming an enlarged head 345. Theenlarged head 345 engages the flange 327 on the interior of the barrel320 when the needle is retracted. In this way, the engagement betweenthe flange 327 and the enlarged head 345 limits the rearwarddisplacement of the needle 365.

Preferably, prior to retraction, the axial distance between the flange327 and the enlarged head 345 is less than the length of the shield 330that projects forwardly from the barrel 320. More specifically,preferably the axial distance is less than half the length of the shieldthat projects forwardly from the barrel 320. It is further preferablethat the axial distance be substantially less than one quarter thelength of the shield that projects from the barrel. In this way, afterretraction, the sharpened tip of the needle is enclosed within theshield 330, rather than being retracted into the barrel 320.

The device 300 further includes elements for impeding re-extension ofthe needle 365 after retraction, so that the contaminated sharpened tipof the needle is not exposed. Specifically, as shown in FIG. 13, theforward end of the actuator button 343 forms a shoulder that engages therearward shoulder of the flange 327 on the interior of the barrel. Asthe needle 365 is retracted, the needle retainer 342 flexes radiallyoutwardly when it is displaced into the larger diameter of the rearwardhalf of the barrel. The rearward edge of the forward half of the barrelforms a lip that operates as a stop engaging the button to prevent theneedle from being displaced axially forwardly.

A connector hub 350 attached to the needle hub 340 provides an accessport for inserting a guide wire 368 through the device 300 and into thepatient. The connector hub 350 includes a central bore in fluidcommunication with the needle 365. In the present instance, the rearwardend of the needle 365 is connected with the connector hub 350.

The connector hub 350 has an open rearward end and preferably forms aconnector in the form of a Luer fitting for attaching a medical device,such as a syringe or guide wire feeder as discussed further below. Inaddition, preferably a lock 356 is formed on the rearward end of theconnector hub for locking the separate device to the connector hub. Morespecifically, preferably, the lock 356 is a threaded Luer lock formed onthe exterior of the connector hub.

In addition, a wire guide 352 is formed in the interior of the connectorhub 350. The wire guide 352 is formed forward of the open end of theconnector hub 350, and includes tapered walls, forming a generallyfrustoconical transition from the open end of the connector hub to asmall diameter opening adjacent to and coaxial with the rearward end ofthe needle. The wire guide 352 operates similar to a funnel, guiding thewire into the small diameter opening of the needle as the wire isinserted through the large opening at the rearward end of the connector.

The connector hub 350 further includes a pair of opposing guide tabs 354projecting radially outwardly into engagement with the guide tracks 328formed in the interior of the barrel 320. The guide tabs 354 cooperatewith the guide tracks 328 to guide the needle 365 rearwardly duringretraction. In addition, the guide tabs 354 and guide tracks 328 operateas a circumferential lock preventing torque applied to the connector hubfrom being transferred to the needle retainer 342. In this way, if afluid collection device, such as a syringe, is attached to the connectorhub 350 by threading the syringe onto the connector hub, the torqueapplied to the connector hub is not transferred to the needle retainer342, which could cause the needle retainer to break or disengage thelocking aperture 322.

In the present instance, the needle hub 340 and connector hub 350 havebeen described as two separate elements connected together. However, thetwo elements can alternatively be formed as a single element.

Retracting the needle into the shield rather than the barrel has severalbenefits. The overall length of the barrel can be reduced because thebarrel need not be long enough to accommodate the retracted needle. Inaddition, the needle 365 provides support for the shield 330 to preventthe shield from collapsing or buckling radially inwardly in response toexternal forces. For instance, the device 300 is used in conjunctionwith a guide wire. The guide wire is inserted vascularly into thepatient through the needle 365. Prior to inserting the guide wire, andwhile the device 300 is inserted in the patient, the medicalprofessional may actuate retraction by depressing the button 343. Theneedle retainer 342 is thereby displaced radially inwardly out ofengagement with the barrel, and the spring 360 displaces the needle 365rearwardly into the retracted position.

As shown in FIG. 13, the needle remains within the shield 330 afterretraction. The shield 330 can then be inserted further into the patientwithout risk of piercing or coring the vein or artery. Depending on thematerial used for the shield and the wall thickness of the shield, theshield may not have sufficient columnar strength to overcome theresistance of inserting the length of the shield vascularly. In suchinstances, the needle provides additional rigidity so that the length ofthe shield can be inserted into the patient. After the length of theshield is inserted into the patient, the guide wire is threaded into thepatient through the retracted needle and the shield.

After use, the shield 330 shields the sharpened tip of the needle 365against inadvertent contact. Preferably, the shield 330 is somewhatflexible. In addition, the shield is preferably formed with sufficientcolumn strength to prevent the shield 330 frown collapsing axially inresponse to an axial force after retraction. This columnar strengthprevents the shield from readily buckling axially after retraction,which could expose the contaminated needle. In other words, the shield330 is preferably laterally flexible, but is substantially axiallyincompressible. In the present instance the shield is formed of Teflon.However, a variety of other known plastic materials may be used to formthe shield.

Configured in this way, the device 300 is preferably used to insert aguide wire as follows. The needle 365 and shield pierce the skin of apatient and the vein or artery of the patient. Upon inserting the needlevascularly, a flash of blood will flow through the device. The bloodflash can be seen, indicating to the medical professional that a vein orartery has been pierced. A medical device, such as a syringe, is thenattached to the connector hub 350 and an amount of blood is withdrawnfrom the patient to ensure that the needle is properly positioned withinthe patient's vein or artery. Alternatively, the syringe can be attachedto the connector hub 350 prior to inserting the needle into the patient.If a syringe is used, the syringe plunger is withdrawn to form a vacuumthat draws blood into the syringe barrel. Preferably, approximately 1–3cc of blood are withdrawn to ensure that the needle is properlypositioned.

After the blood is drawn, confirming that the needle 365 is properlypositioned, the needle is retracted by depressing button 343. The springthen propels the needle 365 and needle hub 340 rearwardly so that thesharpened tip is shielded. The head 345 of the needle hub engages theflange 327 in the barrel 320 to stop the rearward displacement of theneedle. The needle may be retracted so that the sharpened tip isdisposed within the barrel. However, as discussed above, preferably, theneedle tip is retracted into the shield 330. The shield and the shieldedneedle are then further inserted into the patient's vein or artery.Preferably, substantially the entire length of the shield is insertedinto the patient.

After the shield 330 is inserted into the patient, the guide wire 368 isinserted into the patient. First, the syringe is detached from theconnector hub 350. Blood may continue to flow through the connector hub350 after the syringe is detached. The medical professional may controlthe flow of fluid by sealing the back end of the connector hub with hisor her finger until he or she is ready to feed the guide wire. The guidewire 368 is then fed through the connector hub 350. The tapered surfacesof the wire guide 352 guides the guide wire 368 into the needle 365, sothat feeding the wire through the connector hub 350 feeds the wirethrough the needle and shield 330, into the patient. Once the guide wireis inserted into the needle, the guide wire occludes most of the flow ofblood through the device because the internal diameter of the needle ispreferably substantially the same as the external diameter of the wire.After the guide wire is inserted into the patient, the device iswithdrawn from the patient leaving the guide wire within the patient'svein or artery. Since the contaminated needle 365 is shielded, thedevice 300 can be safely disposed of without concern of an inadvertentneedle stick.

Referring now to FIGS. 15–16, a second embodiment of a guide wireinsertion device is designated generally 400. The embodiment is similarto the embodiment 300, except that the second embodiment includes aY-shaped connecting hub 450 having two ports. The two ports allow thedevice to virtually eliminate blood leakage, thereby providing a“bloodless” procedure as discussed in greater detail below.

The device 400 includes a retractable needle 465 for inserting a guidewire 468. The two ports of the connecting hub 450 allows the medicalprofessional to attach a medical device, such as a syringe, to the firstport to draw blood to ensure that the needle is properly placed in avein, and then leave the syringe attached to the first port to preventblood from leaking out the first port. The guide wire can then beinserted through the second port and into the patient. In this way, thedevice 400 substantially reduces or eliminates leakage of blood duringthe procedure.

Many of the elements of the device 400 are the same or similar to theelements of embodiment 300. For instance, the device 400 includes abarrel 420, a needle 465 projecting forwardly from the barrel, a needleshield 430 sheathing the needle, a spring 460 biasing the needlerearwardly, and a needle hub 440 having a needle retainer 442 releasablyretaining the needle in the projecting position against the rearwardbias of the spring.

However, the barrel 420 has a cut-out or slot for receiving the Y-shapedconnector hub 450 having two ports rather than the single port of theconnector hub 350. The connector hub 450 has a “straight through”portion or leg that is configured similarly to the rearward portion ofthe connector hub 350. The straight through portion 451 is axiallyaligned with the barrel 420 and the needle 465. The rearward end of the“straight through” leg 451 is generally open, and forms a connector,such as a Luer connector for attaching a separate medical device, suchas a syringe, as described in connection with the first embodiment. Alock 456, such as a threaded Luer lock formed on the straight throughleg 451 operates to lock the syringe onto the connector hub 450, sealingthe rearward end of the straight through leg.

The second leg of the Y-connector hub 450 is referred to as the Y-leg orfeeder leg 470. The feeder leg 470 is transverse the straight throughleg 451, and is hollow. The feeder leg 470 can be configured similarlyto the straight through leg 451 so that a syringe can be connected tothe feeder leg rather than the straight through leg. However,preferably, the feeder leg 470 includes a hemostasis valve 472 thatoperates as a check valve preventing blood from leaking out the feederleg, while allowing a guide wire 468 to be inserted into the device 400through the feeder leg. A connector 474, such as a Luer hub having aLuer lock 476 is preferably connected to the feeder leg 470, rearward ofthe valve 472. The connector 474 allows a guide wire feeder 480, such asa hoop feeder to be attached to the device, as discussed further below.

In addition, a wire guide 452 is formed in the interior of theY-connector hub 450. The wire guide may be formed to guide the wire fromonly one of the legs into the needle. However, preferably, the wireguide 452 is formed forward of the intersection of the enlarged bores ofthe straight through leg 451 and the feeder leg 470. The wire guide 452is formed of tapered walls, forming a generally frustoconical transitionfrom the large bores of the straight through leg 451 and the feeder leg470 to a small diameter opening adjacent to and coaxial with therearward end of the needle. The wire guide 452 operates similar to afunnel, guiding the wire into the small diameter opening as the wire isinserted into the large opening in either the feeder leg 470 or thestraight through leg 451.

Configured in this way, the device 400 is operable to insert a guidewire 468 as follows. The needle 465 and shield 430 pierce the skin of apatient and the vein or artery of the patient. Upon inserting the needlevascularly, a flash of blood will flow through the device. A medicaldevice, such as a syringe, is then attached to the connector hub 450 andan amount of blood is withdrawn from the patient to ensure that theneedle is properly positioned within the patient's vein or artery.Alternatively, the syringe can be attached to the connector hub 450prior to inserting the needle into the patient. If a syringe is used,the syringe plunger is withdrawn to form a vacuum that draws blood intothe syringe barrel. Preferably, approximately 1–3 cc of blood iswithdrawn to ensure that the needle is properly positioned.

After the blood is drawn confirming that the needle 465 is properlypositioned, the needle is retracted by depressing button 443. The springthen propels the needle 465 and needle hub 440 rearwardly so that thesharpened tip is shielded. The head 445 of the needle hub engages theflange 427 in the barrel 420 to stop the rearward displacement of theneedle. The needle may be retracted so that the sharpened tip isdisposed within the barrel. However, as discussed above, preferably, theneedle tip is retracted into the shield 430. The shield and the shieldedneedle are then further inserted into the patient's vein or artery.Preferably, substantially the entire length of the shield is insertedinto the patient.

After the shield 430 is inserted into the patient, the guide wire 468 isinserted into the patient. The guide wire 468 is fed through the feederleg 470. The tapered surfaces of the wire guide 452 guides the guidewire 468 into the needle 465, so that feeding the wire through thefeeder leg 470 feeds the wire through the needle and shield 430, intothe patient.

Since the guide wire 468 is not fed through the straight through leg451, the syringe need not be removed from the Y-connector hub, so thatthe syringe seals the straight through leg, preventing blood fromleaking out the straight through leg. In addition, the valve 472attached to the feeder leg 470 prevents blood from leaking out thefeeder leg as the guide wire is inserted into the patient. In this way,the device 400 is operable to achieve a “bloodless” method of insertinga guide wire into a patient, wherein little or no blood leaks from thedevice during use. In addition, after use, the sharpened tip of theneedle 465 is shielded to prevent inadvertent needle sticks with thecontaminated needle.

In FIGS. 17–18, the device 4000 is illustrated in use in a patient. InFIG. 17, the device 400 is illustrated in connection with a hoop feeder480. The device is shown after vascular insertion, in which the needle465 and shield 430 have pierced the patient's skin 405 and vein orartery 407. In FIG. 18 the shield 430 is shown partially broken awaywith the needle 465 retracted into the shield. In FIGS. 17 and 18, theguide wire 468 is shown being inserted into the patient with the shield430 only partially advanced into the patient. However, preferably,substantially the entire length of the shield 430 is inserted into thepatient prior to inserting the guide wire.

Referring again to FIG. 17, a hoop feeder 480 is shown. The hoop feederincludes a connector 482, such as a male Luer connector, that mates withthe Luer connector 474 on the feeder leg 470 to attach the hoop feederto the device 400. The hoop feeder 480 also includes a length of guidewire 468 sheathed by one or more convolutions of a casing, such as aplastic casing 485. A cut-out or window 487 in the casing 485 providesaccess to the guide wire 468. The medical professional engages the guidewire 468 in the window 487 to advance the guide wire into the patientthrough the device.

In FIG. 17, the device 400 is also shown in connection with a dead-endconnector 490 attached to the rearward end of the straight through leg451. Such a dead-end connector can also be attached to the connector hub350 of the previous embodiment. The dead-end connector 490 seals thestraight through leg 451 to prevent blood from leaking out the straightthrough leg. The dead-end connector can be attached to the straightthrough leg after blood is drawn into a syringe. For such use, thesyringe is detached after the blood is drawn, and the dead-end connectoris attached in place of the syringe.

Alternatively, and preferably, the dead-end connector 490 includes ahollow interior forming a reservoir for receiving blood. A vent plug 492in the form of a hydrophobic filter prevents blood from leaking out theback end of the dead-end connector, while allowing air to flow throughto prevent the connector from becoming line locked, so that blood canflow into the connector. Preferably the connector 490 is transparent ortranslucent so that the medical professional can see the blood flowinginto the connector.

The dead-end connector 490 can be used in one of several ways. First,the connector 490 can operate as a flash-back chamber. In this manner,the dead-end connector 490 is attached to the straight through leg 451prior to piercing the patient with the needle 465. After the medicalprofessional pierces the patient with the needle and sees a flash ofblood in the connector, the connector is removed and a syringe orsimilar device is attached to the straight through leg 451 to draw bloodto ensure that the needle 465 is properly positioned.

Alternatively, the dead-end connector 490 can operate as the indicatorthat the needle is properly positioned within the patient's vein orartery. In this manner, if blood flows adequately into the dead-endconnector 490, the medical professional retracts the needle and theninserts the shield further into the patient. Since the connector 490operates as the blood flow indicator, a syringe need not be attached,and the dead-end connector 490 remains attached to the straight throughleg 451 to seal it against blood leakage.

Referring again to FIG. 18, the device 400 is illustrated without afeeder, such as the hoop feeder 480 illustrated in FIG. 17. In such use,the medical professional inserts the guide wire 468 by grasping the wireand feeding the wire into the feeder leg. Preferably the medicalprofessional uses a tool to grasp the wire. In one manner, the medicalprofessional grasps the wire with tweezers, advancing the wire with thetweezers, then releasing the wire and re-grasping the wire rearward toadvance more of the guidewire.

FIG. 18 also illustrates an alternative and preferred tool 495 forgrasping the guide wire to feed the guide wire. The gripping tool 495 isformed of a plastic material, and is preferably formed of an elastomericmaterial so the it is resilient. The gripping tool comprises a pair ofjaws 497 for gripping the wire, and a through-bore for receiving theguide wire 468. The through bore is sized slightly larger than the wirediameter so that the wire can readily pass through the gripper 495.

By grasping the sides of the gripper 495, the gripper clamps onto theguide wire 468 so that the medical professional can advance the wireinto the patient. After advancing the guidewire 468, the medicalprofessional releases his or her grip of the gripper, which releases thegripper jaws 497 from clamping onto the wire. The medical professionalthen slides the gripper rearwardly along the wire, then squeezes thegripper to grasp the wire to advance the wire further into the patient.Additionally, preferably the forward portion of the gripper forms a noseconfigured to cooperate with the open end of the feeder port 470.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation. There is no intention in use of suchterms and expressions of excluding any equivalents of the features shownand described or portions thereof. It is recognized, however thatvarious modifications are possible within the scope and spirit of theinvention as set forth in the following claims.

1. A medical device, comprising: a hollow housing; a needle having a sharpened tip projecting forwardly from the housing; a biasing element biasing the needle rearwardly; a needle retainer releasably retaining the needle against the rearward bias of the biasing element; a flexible shield fixedly attached to the housing, projecting forwardly from the housing; the shield being configured for insertion into a patient; the shield sheathing the needle such that in a projecting position, the sharpened tip of the needle projects beyond a forward edge of the shield, and in a retracted position the sharpened tip is enclosed within the shield; wherein upon actuation of the needle retainer, the biasing element displaces the needle rearwardly so that the sharpened tip of the needle is enclosed within the shield, wherein the shield is substantially puncture resistant wherein the axial force required to buckle the shield is less than the force necessary to puncture the shield with the needle to prevent inadvertent contact with the contaminated needle.
 2. A medical device, comprising: a hollow housing; a needle having a sharpened tip projecting forwardly from the housing; a biasing element biasing the needle rearwardly; a needle retainer releasably retaining the needle against the rearward bias of the biasing element; a shield fixedly attached to the housing, projecting forwardly from the housing; the shield being configured for insertion into a patient; the shield sheathing the needle such that in a projecting position, the sharpened tip of the needle projects beyond a forward edge of the shield, and in a retracted position the sharpened tip is enclosed within the shield wherein the axial force required to buckle the shield is less than the force necessary to puncture the shield with the needle to prevent inadvertent contact with the contaminated needle; a stop operable to impede rearward displacement of the needle after the needle is displaced into the retracted position, wherein the stop is positioned so that the distance that the needle is displaced from the projecting position to the retracted position is substantially less than the length of the needle; wherein upon actuation of the needle retainer, the biasing element displaces the needle rearwardly so that the sharpened tip of the needle is enclosed within the shield. 